Total Synthesis of Reported Structure of Baulamycin A and Its Congeners.

A convergent and flexible strategy for the stereoselective total synthesis of the reported structure of baulamycin A and its congeners has been developed for the first time. Synthetic highlights include a Crimmins aldol reaction to construct the C-1' and C-14 centers, a Crimmins acetate aldol reaction to generate the hydroxy group at the C-13 position, Horner-Wadsworth-Emmons olefination to form the C9-C10 bond, and Evans methylation to install the C-8 center. This synthetic study disclosed that the reported structure of baulamycin A needs to be revised, as its spectroscopic data are not identical with those of the synthetic baulamycin A.